The actual cost for producing electric energy varies very strongly between tenths of one Swedish ore (1 Skr=100 ore) per KwH during the spring flood and night time and 15-20 ore per kwh during periods of high demand and dry years. Today the consumer is charged a fixed energy price during the whole year based on the long-term marginal cost calculated from a co-ordination of all electric energy producers of the country. This pricing is not based on the actual cost, but it has hitherto been the only possible realistic pricing system.
A condition for a pricing system which charges the consumer the actual instantaneous energy cost is however a communication system between the distributor and the consumer of electric energy. Modern computer technique has made central and automatic reading and registration of a consumer's consumption possible whereby the ordinary distribution line between the electric power station and the consumer is used as a communication medium.